National 5 Biology
Unit 1
Proteins and Enzymes
SUCCESS CRITERIA
(What you are learning)
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Success Criteria
State that each protein is built up from a large number of
subunits called amino acids.
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State that hundreds of amino acid molecules are joined
together into chains, called polypeptides, by strong peptide
bonds.
State that during the process of protein synthesis, each
polypeptide is built up from a particular genetically-determined
sequence of amino acids.
State that the sequence of amino acids determines the protein’s
shape and function.
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State that proteins are found within the membranes of all cells
and provide a vital structural role.
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State that hormones are proteins that act as chemical
messengers and are transported in an animal's blood to 'target'
tissues where they carry out a regulatory effect on growth and
metabolism.
State that antibodies are proteins made by white blood cells
called lymphocytes They are made to defend the body against
antigens.
State that biochemical processes in living things, such as
photosynthesis or respiration, are controlled by enzymes. Every
enzyme is made of protein.
State that an enzymes function as biological catalysts
because they speed up the rate of all biochemical reactions in
living organisms.
State that enzymes are made by all living cells.
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State that they take part in a reaction but remain unchanged at
the end of it.
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State that the active site of an enzyme is the place on the
enzyme's surface which matches the shape of the substance
that it works on (its substrate).
State that an enzyme is said to be specific to its substrate as
each enzyme is able to act on only one type of substrate.
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State that the substrate is the only substance whose molecules
exactly fit the enzyme's active site. So the substrate's molecular
shape is said to be complementary to the enzyme's active
site.
State that at very low temperatures, enzyme molecules are
inactive but undamaged.
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State that as the temperature increases, the rate of reaction
increases.
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State that the temperature at which the enzyme works at its
fastest rate is called the optimum temperature. The optimum
temperature for most human body enzymes is 370C.
State that enzymes are proteins and the structure of proteins is
easily changed by heating, e.g. as seen when boiling an egg.
This results in a change in their shape. This effect is permanent.
The protein is said to be denatured, and this is irreversible.
State that beyond the optimum temperature, as more and more
enzyme molecules become denatured, the rate of reaction
decreases rapidly.
State that enzymes work within a range of pH values. Each
enzyme works best at its optimum pH
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State that the shape of an enzyme, or protein, can be changed
by changes in the pH of the solution it is in. This will affect the
rate of reaction between the enzyme and substrate and may
result in the enzyme becoming denatured.